And train-control system



C. H. WOODWARD.

TRAIN SIGNALING AND TRAIN CONTROL SYSTEM.

APPLICATION FILED OCT. 18. 1915.

Patented Jan. 27, 1920.

1 mil/L17 CHARLES WOODWARD, OF BOURNEMOUTH, ENGLAND.

TRAIN-SIGNALING- .AND TRAIN-CONTROL SYSTEM.

Specification of Letters Patent.

Patented Jan. 27, 1920.

Application filed October 18, 1315. Serial No. 56,649.

To all whom it may concern:

Be it known that I, CHARLES HnMLn'r Wooownno, a citizen of the UnitedKingdom, residing at 15 Richmond Park Crescent, Bournemouth, in thecounty of Hampshire, England, have invented a new and usefulTrain-Signaling and Train-Control System, of which the following is aspecification.

This invention relates to a novel train signalii'lg and train controlsystem, and according to the invention the indicating or controllingcircuit on the train is energized by the instantaneous difference ofpotential between the points of a track rail or between two rails onwhich high frequency alternating current is impressed by suitable means,the said circuit being tuned in resonance with the periodicity of thealternation. If one end of the track rail is directly connected to thesource of the high frequency current the other end may be grounded overa condenser of adjustable capacity. In this case the track rail formspart of a closed oscillatory circuit with practically no radiation; orwhere a closed oscillating circuit is used as a generator, the tuningcondenser may be omitted when the rail will operate as a couplingbetween the generating and receiving circuits. The train carriedindicating or power con trolling devices are inserted in a circuitconnected to two points on the track rail or rails from which the highfrequency current can be collected by conductors carried by the trainrunning on the rail or rails. For example, the circuit can be completedthrough the trainwheels or other conductors running on the track, and ifcompleted through the wheels, the circuit can be traced from one wheelthrough its axle box to the indieating or control devices back to therail through another wheel and its axle box. Owing to the well knownskin eflect of an iron conductor on which high frequency oscillationsare impressed, caused by the high impedance. a considerable differenceof potential will obtain between two points at a comparatively smalldistance apart, with an alternating current of high frequency, therebycausing the connected circuit to swing powerfully when tuned.

The arrangement is preferably such that safety conditions are indicatedby the pres ence of current in the receiving circuit and, conversely,danger conditions by the absence of such current; such absence ofcurrent being caused by switch operation, breakage of apparatus,detuning of the resonant circuit or circuits.

When more than one independent signal is required, each track rail maybe connected, as described above, but the oscillations impressed on thetwo rail circuits will be tuned to different frequencies to avoidresonant interference between the two circuits. Therefore, both rails orsections may be used separately or together.

A third independent set of signals may be obtained by joining the twotrack rails or sections through a condenser at the end of a section andtuning its train carried receiving circuit to a suitable frequency ofthis closed circuit to avoid resonant interference with the othercircuits. Or, if the rail be used as a common coupling between thereceiving circuits and a closed generating circuit, the condenser may beomitted and the rails directly connected. The receiving circuit willhave a portion consisting of axle, truck, or other metallic frameworkcommon to itself and the rail circuit, and must in either case be tunedto a frequency different from that impressed on either rail separatelyand such as to avoid resonant interference with the other rails orsections. It is obvious that this set of signals can be receivedindependently of those transmitted over either or both of the separaterails. Also, one or both rails may be cut at any point and signalsreceived over that par ticular length of rail. For the purpose describedor for additional signal indications or the like, one or both rails orsectionsmay by known arrangement be cut at any point and used in theaforementioned manner for the purpose of interlocking the operations ofthe aforementioned signal or the like indications or control and use maybe made of high frequency alternating current whereby a train in a givenblo k may cut off or control the power in a block in the rear and also.if desired, any other section in the rear or advance.

It is well understood that a change in the length of rail over which thecurrent would pass would cause an increase in the frequency of thecurrent in the track circuit, hence, inasmuch as the cab circuit isnormally tuned to the frequency impressed on the track rail under clearconditions it must,

in view of what has just been said, be neces sarily tuned to the lowestfrequency impressed on the track rail.

The signals received ma be used in known manner to apply the bra es, tocontrol the motive power applied to the train, or give audibleindications by means of bells or whistles, or visual indications bylamps or the like or otherwise.

The accompanying drawings represent diagrammatically examples of circuitarrangements embodying my invention.

In said drawings:

Figure 1 illustrates an arrangement in which the train carried circuitis energized by the potential difference between points on the minetrack rail.

Fig. 2 illustrates an arrangement in Which the train carried circuit isenergized by the potential difference between points on two track rails.

As shown in said drawings, and referring more particularly to Fig. 1,10, 11 designate the track rails and 14, 15 designate, respectively, thefront and rear axles of a portion of a train traveling on said trackrails. 16, 16 designate low tension alternatin electric current leadsand 17 and 18 designate, respectively, the primary and secondarywindings of a ste -up transformer, in which the primary win ing isconnected across the leads 16. 19 designates a spark gap in thesecondary circuit of the transformer; 20 an adjustable condenser in saidcircuit and 21 an inductive resistance in the circuit traversed by thehigh frequency oscillations set up by the spark gap. These oscillationsare impressed on the track rails and adjustable condensers 22 areconnected to the rails at a distant point. The condensers may beconnected to ground. As shown in Fig. 1, the rails 10 and 11 arerespectively parts of separate circuits through which two train carriedcircuits may be simultaneously energized, but either of the energizingcircuits may be used to the exclusion of the other.

In the arrangement shown in Fig. 2, high frequency oscillations areadditionally impressed On the two track rails 25, 26, which rails may beconnected at a distant point through an adjustable condenser 27. Aninductive resistance 28 and a spark gap 29 is connected between therails. In other res ts the arrangement shown in Fig. 2 is like thatshown in Fig. 1, and the operation in Fig. 2 is modified with respect toFig. 1 in the manner hereinafter described.

Referring again to Fig. 1, it will be noted that the train carriedcircuit or circuits is energized by the instantaneous potentialdifference between the points on the track rail or rails in electricconnection, respectively, with the axle boxes or axles 14 and 15,through the wheels of said axles which travel on the said rails orthrough other conductors that travel on the track rails.

Each said train carried circuit comprises an inductance 30, anadjustable condenser 31, and a relay coil 32. Each circuit is tuned tothe frequency of the oscillations impressed on its corresponding rail toavoid resonant interference. When the relay windings 32 are energized anaudible or visual signal may be operated in any well known manner bycompleting the circuit of a battery 33, thereby operatlng a member 3-1,diagrammatically shown, whlch member may be operated to control a visualor audible signal, or may also be arranged in any well known manner toapply the brakes or control the motive power applied to the train, oneof said members 34 being adapted to a signal and the other to a controldevice.

The train controlled circuit shown in Fig. 2 is similar to that shown inFig. 1, with the exception that it further embraces a third circuit thatis energized by the potential difference between two points respectivelyon the track rails 25 and 26, in electrical connection respectively withthe boxes of the axle 15 or other conductors that travel in contact withthe rails. The third circuit will, of course, be tuned to its actuatingcircuit to avoid resonant interference with the other circuits.

Instead of the track coupling shown in Figs. 1 and 2, between the sparkgap circuit and the track circuit, an oscillation transformer may beintroduced between the two circuits in the manner usual in transmissionor reception of electro magnetic 00 waves for signaling without wires.In this event, the condenser 22 of Fig. 1 may be omitted.

It is obvious that any method of generating high frequency current maybe em- 105 ployed without departing from the primerples of theinvention.

I claim as my invention:

1. A system of electric signaling or power control comprising means toimpress high 110 frequency oscillations on the track rail, and a traincarried circuit having contacts to travel on the track rail andenergized by the instantaneous potential difference between two pointsof the rail engaged by 115 said contacts, the train carried circuitbeing tuned to the frequency of the rail circuit.

2. A system of electric signaling or power control set forth in claim 1,wherein each of two track rails are traversed by current 120 ofdifferent periodicities and the rail circuits are tuned similarly to thetrain carried circuits to avoid resonant interference.

3. A system of electric signaling or control set forth in claim 1wherein both track 125 rails form part of a circuit tuned to a frequencydifferent from the circuit comprising a single rail only.

4. A system of electric train signaling or power control comprising, incombination 130 with a track rail, means to include said rail as a partof a closed oscillatory circuit and a circuit carried by the train incontact with and tuned to resonate with the closed oscillatory railcircuit.

5. In a system of electric train signaling or power control, means toinclude the rail of the track as part of a closed resonant oscillatorycircuit, said resonant circuit becoming detuned to indicate dangerconditions.

6. A system of electric train signaling or power control comprisingmeans to impress high frequency oscillations on the two rails of thetrack, the frequency in the track circuit being controlled by thepresence of a train in the rail block.

7. In a system of electric train signaling or power control, means toinclude the two rails of the track as part of a closed resonantoscillatory circuit, and a train carried circuit having contacts totravel on the track rails and energized by the instantaneous potentialdifference between points on the rails engaged by said contacts.

8. A system of electric cab signaling 01' power control comprising meansto independently impress on the two rails of a track high frequencyoscillations of different periodicity, adapted for use in connectionwith a plurality of circuits carried by a train or trains on the track,respectively, tuned in resonance to the high frequency oscillations ofthe two track circuits.

9. A system of electric cab signaling or power control comprising anadjustable condenser connected to the rail and to the ground, means toimpress high frequency oscillations on the rail at a point distant fromthe condenser, and a circuit carried by the train and energized from thetrack rail the train carried circuit being tuned to the high frequencyoscillations.

10. A system of electric signaling or power control set forth in claim1, wherein the train carried circuit is tuned to the lowest frequency ofthe rail circuit.

C. H. WOODWARD.

lVitnesses HARVEY J. BAvERs'rooK, CHARLES BLACK.

